Cilia and flagella are complex microtubular organelles that are ubiquitous among eukaryotes, including humans, where they are found in the respiratory tract, the female reproductive tract and on sperm cells. Ciliary and flagellar dysfunction resulting from the absence of dynein arms has been reported to cause respiratory and fertility problems in humans and other mammals. Movement of cilia and flagella is driven by a complex group of molecular motors, the axonemal dyneins. The long-term objectives of this work are to understand the role(s) each different dynein play in ciliary and flagellar motility and how the functions of those dyneins are regulated during changes in ciliary and flagellar behavior. We will attempt to answer those questions by using targeted gene knockout techniques to introduce germ-line mutations into six genes encoding the 1-headed inner arm dynein heavy chains in the unicellular protozoan, Tetrahymena thermophila. The specific aims of this project are: I. Generate germ line disruptions of the tethering domain in six 1-headed inner arm dynein heavy chain genes (DYH 8-13) in Tetrahymena thermophila. II. Determine the role each dynein HC plays in normal ciliary movement by analyzing swimming speed, beat frequency, and feeding rate of each mutant strain. III. Test the model that the 11 and I2/3 inner arms act antagonistically during Ca++-mediated decreased swimming speed, ciliary arrest, and reversal of ciliary beat. IV. Determine the organization of inner arm dyneins in the 96 nm repeat by performing TEM analyses of I2/3 mutants. The results of this work should add to our understanding of the function and regulation of the inner arm dyneins in cilia and flagella [unreadable] [unreadable]